2008 Joint Meeting of The Geological Society of America, Soil Science Society of America, American Society of Agronomy, Crop Science Society of America, Gulf Coast Association of Geological Societies with the Gulf Coast Section of SEPM

Paper No. 14
Presentation Time: 8:00 AM-4:45 PM

Refining the Temporal and Spatial Evolution of the Teton Range, Wyoming, from Integrated Apatite (U-Th) / He and Structural Analyses

BROWN, Summer J., SPOTILA, James, THIGPEN, J. Ryan and TRANEL, Lisa M., Department of Geosciences, Virginia Tech, 4044 Derring Hall, Blacksburg, VA 24061, summerb@vt.edu

Although the Teton fault is the main source of uplift of the Teton Range, uncertainties exist regarding the timing and displacement magnitude of the major SE-dipping normal fault. Furthermore, the dramatic relief of the Tetons raises questions regarding the regional exhumation history and, more broadly, the kinematics of how normal faults evolve. The unique topography of the range is a result of relatively recent uplift coupled with altitude and climate-dependent erosional mechanisms, making the Tetons an exceptional location for investigating the interaction between tectonics, climate, and erosion. Detailed structural reconstruction of the Paleozoic unconformity (present throughout the range) reveals limits for uplift and maximum denudation of the Teton Range. This, combined with low-temperature thermochronolgical constraints on the timing and rate of uplift of the fault block, allows us to define the total erosional budget and relief production since the initiation of uplift. Early efforts at quantifying the evolution of the Teton Range revealed differential uplift rates between the northern and southern parts of the range; however, because apatite fission-track records the time since the last thermal event of temperatures greater than ~105°C, questions remain unanswered regarding the most recent stages of uplift. Therefore, we utilize (U-Th)/He dating of apatite because of its notably low closure temperature of ~75°C and He partial retention zone between ~40–75°C. Preliminary results from a series of transects across the Tetons help to deduce the history and long-term uplift rate, while future data from an along-strike transect may help clarify ideas about the temporal and spatial evolution of normal faults. These results, coupled with structural analyses and recent field observations, provide essential insight into the evolution of the Teton landscape.